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Mid-rotation silvicultural treatments (MRT) are commonly applied to loblolly pine (Pinus taeda L.) plantations in the southeastern United States to improve pine productivity. Competing vegetation is often present in operational plantations and limits site resource availability. The benefits of MRT for pine productivity are well known, but competing vegetation growth has not been extensively studied. Pine and competing vegetation growth within two regions of the southeastern United States was monitored for 8 years following a one-time post-thin application of either fertilization (224 kg ha-1 of nitrogen plus 28 kg ha-1 phosphorus), chemical herbicide (0.8 oz glyphosate and 0.8 oz triclopyr L-1 of water) or their combination. Fertilization significantly increased pine volume growth in the Lower Coastal Plain (LCP, 2.67-4.01 m3ha-1yr-1) and the Upper Coastal Plain/ Piedmont (UCPIE, 0.20-3.72 m3ha-1yr-1). Chemical herbicide application in both the LCP (0.34-4.87 m3 ha-1yr-1) and UCPIE (0.89-1.97 m3 ha-1yr-1) also significantly increased pine volume. Chemical herbicide application, individually and combined, did not result in significant decreases in herbaceous vegetation, but reduced woody vegetation by up to -2.40 m3 ha-1yr-1 in the LCP and -5.67 m3 ha-1yr-1 in the UCPIE. Consequently, we suggest that competing vegetation response should be considered within site-specific management plans aimed at maximizing pine productivity. [ABSTRACT FROM AUTHOR]

The invasive Oomycete pathogen Phytophthora ramorum has killed millions of susceptible oak and tanoak trees in California and southern Oregon forests and is responsible for losses in revenue to the nursery industry through mitigation activities. In addition, infestation of forests in the United Kingdom by this organism has resulted in the destruction of many hectares of larch plantations. Resprouting stumps can be a reservoir for the inoculum of P. ramorum persisting on a site. In areas where the application of herbicides is not permitted, a biocontrol treatment would be an indispensable alternative. Treatment of stumps with the sap-rotting fungus Chondrostereum purpureum (Pers.) Pouzar has been shown to be an effective tool for the suppression of resprouting on several species, most notably red alder. In this project, the ability of C. purpureum to suppress resprouting was evaluated on stumps of two host species, tanoak (Notholithocarpus densiflorus) and California bay laurel (Umbellularia californica). Laboratory testing of three California isolates of C. purpureum indicated that the fungus can colonize bay laurel stems. Field trials were established near Brookings, Oregon, on tanoak and on bay laurel near Soquel, California. Early results of field testing showed that C. purpureum was able to colonize the stumps of tanoak following treatment and was found to occur naturally on tanoak logs and stumps. Formulations of C. purpureum appear to have some effect on reducing sprout survival in tanoak, but the most effective and rapid treatment for this host is the hack and squirt method of applying the herbicide imazapyr. Sprayed herbicide prevents sprouting on bay laurel, and there was evidence that resprouting was inhibited on stumps treated with C. purpureum. Over time, applications of C. purpureum may be a more permanent solution as the stumps begin to decay. [ABSTRACT FROM AUTHOR]

Although herbicides have extensively been used in forest landscape restoration, its effects and opportunity costs have rarely been studied in Ghana. This study evaluated types of herbicides used, assessed the perceptions of the effects of herbicide usage among farmers enrolled in a taungya (i.e. farm forestry programs) in the dry semi-deciduous ecological zone of Ghana. The study also analyzed the challenges associated with the application of herbicides and determined the impact of socio-economic factors that influence farmers decision to use herbicides on farms. Data were collected from 300 taungya farmers and 20 herbicide traders in Offinso North, Offinso South, and Techiman South Municipal. Data collection was completed in December 2016. Data were analyzed descriptively and quantitatively. Results indicate that 100% of farmers perceived herbicides as having deleterious effects on flora (seedlings, under-storey wild foods, medicines) and fauna (soil micro-organisms, fish in rivers) as well as water quality, soil structure and human health. Nevertheless, 93% of them use herbicides to reduce labour costs and to establish larger acreages. Based on their functional properties, 85% of herbicides traded are non-selective for bush clearing and 15% are selective for weeding. Farmers use them indiscriminately due to poor knowledge on recommended practices and intensity of invasiveness of weed species. Education, residential status and age of respondents significantly predicted usage. The study recommends a review of Ghana's pesticide deployment strategies and herbicides guide book for use in farm forestry. Capacity of frontline forestry professionals, traders and farmer-based organizations must be enhanced to effectively advice and monitor safe application. Plant based herbicides must be promoted for safety and enhancement of biodiversity.

The invasive Oomycete pathogen Phytophthora ramorum has killed millions of susceptible oak and tanoak trees in California and southern Oregon forests and is responsible for losses in revenue to the nursery industry through mitigation activities. In addition, infestation of forests in the United Kingdom by this organism has resulted in the destruction of many hectares of larch plantations. Resprouting stumps can be a reservoir for the inoculum of P. ramorum persisting on a site. In areas where the application of herbicides is not permitted, a biocontrol treatment would be an indispensable alternative. Treatment of stumps with the sap-rotting fungus Chondrostereum purpureum (Pers.) Pouzar has been shown to be an effective tool for the suppression of resprouting on several species, most notably red alder. In this project, the ability of C. purpureum to suppress resprouting was evaluated on stumps of two host species, tanoak (Notholithocarpus densiflorus) and California bay laurel (Umbellularia californica). Laboratory testing of three California isolates of C. purpureum indicated that the fungus can colonize bay laurel stems. Field trials were established near Brookings, Oregon, on tanoak and on bay laurel near Soquel, California. Early results of field testing showed that C. purpureum was able to colonize the stumps of tanoak following treatment and was found to occur naturally on tanoak logs and stumps. Formulations of C. purpureum appear to have some effect on reducing sprout survival in tanoak, but the most effective and rapid treatment for this host is the hack and squirt method of applying the herbicide imazapyr. Sprayed herbicide prevents sprouting on bay laurel, and there was evidence that resprouting was inhibited on stumps treated with C. purpureum. Over time, applications of C. purpureum may be a more permanent solution as the stumps begin to decay.

The time consumption (TC) of pre-commercial thinning (PCT) varies greatly among sites, stands and forest workers. The TC in PCT is usually estimated by field-assessed work difficulty factors. In this study, a linear mixed model for the TC in PCT was prepared by utilizing forest resources data (FRD). The modelling data included 11 848 and validation data included 3035 worksites with TC information recorded by forest workers within the period of 2008–2018. The worksites represented a range of site and stand conditions across a broad geographical area in Finland. Site and stand characteristics and previous management logically explained the TC in PCT. The more fertile the site, the more working time was needed in PCT. On sites of medium fertility, TC in the initial PCT increased with stand age by 0.5 h ha–1 yr–1. Site wetness increased the TC. PCT in summer was more time consuming than in spring. Small areas were more time consuming to PCT per hectare than larger ones. The between-forest worker variation involved in the TC was as high as 35% of the variation unexplained by the TC model. The coefficient of determination in validation data was 19.3%, RMSE 4.75 h ha–1 and bias –1.6%. The TC model based on FRD was slightly less precise than the one based on field-assessed work difficulty factors (removal quantity and type and terrain difficulty): RMSE 4.9 h ha–1 vs. 4.1 h ha–1 (52% vs. 43%). The TC model could be connected to forest information systems where it would facilitate the predictions of the labour costs of PCT without field-assessing work difficulty factors.

Site preparation is used to favor seedling regeneration and establishment by enhancing growing conditions and increasing resource availability, yet few studies have compared different site preparation techniques on growth and yield of trees over multiple decades. We destructively sampled 34-year old trees of western white pine (Pinus monticola Douglas ex D. Don) and Interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco planted at two sites using a replicated experiment to test the effectiveness of different site preparation treatments: (1) no site preparation, (2) scalping, (3) bedding, and (4) bedding plus three years of competition control with herbicide. Growth and yield were compared among the treatments, and models of growth were developed for each species and treatment combination. The herbicide treatment was the only treatment that consistently improved growth and yield of both species resulting in 19%–30% gains in height, 43%–63% gains in diameter, and 31%–109% gains in stem volume by age 34. Height growth response to herbicide was sustained until age 14 for white pine and age 12 for Douglas-fir, while the diameter response was sustained until age 23 for white pine and 20 for Douglas-fir. The later peak in growth for white pine suggests a better response to treatment and that the species was able to maintain higher growth following crown closure. Both species exhibited a Type 2 growth response to herbicide, suggesting competition control resulted in sustained gains over time with associated age shifts of 8.5 and 9.7 years for white pine and 7.1 and 10.2 years for Douglas-fir, height and diameter, respectively. This compares to scalping and bedding which produced no detectable difference in growth compared to the control, and in some instances, reduced growth. In the Northern Rocky Mountains, moisture is most limiting. This is likely why trees showed the greatest response to competition control. Interestingly, this growth was sustained well beyond seedling establishment.

Water stress integral (WSI) is a method of assessing cumulative plant water stress over a chosen period of time. While the technique has been used in other tree species, it has not been applied for reforestation projects. In this study we used the WSI approach for newly planted Douglas-fir in the Pacific Northwest (USA), where the Mediterranean climate, plant community development, and competition for water all play key roles in the success of establishment efforts. In this study, previously reported seedling growth, xylem water potential, and soil moisture data were utilized to provide direct correlations between Douglas-fir productivity, soil water availability and WSI. For each growing season, a strong relationship between WSI and volume growth as well as a strong linear relationship between WSI and soil moisture measured during mid-August was found. On average, for each reduction of 0.01 cm3 cm−3 in soil moisture measured during mid-August, Douglas-fir seedling volume growth decreased by 5.6 and 7.7% in the first and second growing seasons, respectively. Preserving soil moisture until early-August through the judicial application of vegetation management regimes was critical for maximizing stand productivity. Based on these results, a single evaluation of soil volumetric water content during early-August can be used as a predictor of stand productivity during the initial two seasons of forest establishment. [ABSTRACT FROM AUTHOR]

Glyphosate-based herbicides are the dominant products used internationally for control of vegetation in planted forests. Few international, scientific syntheses on glyphosate, specific to its use in planted forests, are publically available. We provide an international overview of the current use of glyphosate-based herbicides in planted forests and the associated risks. Glyphosate is used infrequently in planted forests and at rates not exceeding 4 kg ha-1. It is used within legal label recommendations and applied by trained applicators. While the highest risk of human exposure to glyphosate is during manual operational application, when applied according to label recommendations the risk of exposure to levels that exceed accepted toxicity standards is low. A review of the literature on the direct and indirect risks of operationally applied glyphosate-based herbicides indicated no significant adverse effects to terrestrial and aquatic fauna. While additional research in some areas is required, such as the use of glyphosate-based products in forests outside of North America, and the potential indirect effects of glyphosate stored in sediments, most of the priority questions have been addressed by scientific investigations. Based on the extensive available scientific evidence we conclude that glyphosate-based herbicides, as typically employed in planted forest management, do not pose a significant risk to humans and the terrestrial and aquatic environments. [ABSTRACT FROM AUTHOR]

Arundo donax (L.), also known as giant reed, is a tall, fast-growing, bamboo-like grass that under ideal conditions can reach a height of up to 30 feet and a stem diameter up to 1.5 inches. Giant reed is invasive and difficult to control and has caused economic losses in California, Nevada, Utah, Arizona, New Mexico, and Texas. This species was introduced to Florida over 100 years ago and is currently naturalized in at least 26 of the 67 Florida counties. So far, giant reed has not proved problematic in Florida, but recent permitting of its planting for bioenergy feed stock may increase the risk that it could naturalize into plant communities in Florida and other southeastern states and potentially cause economic losses as well as harm to native species and habitats. This 5-page fact sheet describes the biology of this species and explains some strategies for its control. Written by Pat Minogue and Seth Wright and published by the School of Forest Resources and Conservation, March 2016. FOR328/FR396: Biology, Control and Invasive Potential of Giant Reed (Arundo donax L.) in Florida (ufl.edu)

Glyphosate-based herbicides are the dominant products used internationally for control of vegetation in planted forests. Few international, scientific syntheses on glyphosate, specific to its use in planted forests, are publically available. We provide an international overview of the current use of glyphosate-based herbicides in planted forests and the associated risks. Glyphosate is used infrequently in planted forests and at rates not exceeding 4 kg ha1. It is used within legal label recommendations and applied by trained applicators. While the highest risk of human exposure to glyphosate is during manual operational application, when applied according to label recommendations the risk of exposure to levels that exceed accepted toxicity standards is low. A review of the literature on the direct and indirect risks of operationally applied glyphosate-based herbicides indicated no significant adverse effects to terrestrial and aquatic fauna. While additional research in some areas is required, such as the use of glyphosate-based products in forests outside of North America, and the potential indirect effects of glyphosate stored in sediments, most of the priority questions have been addressed by scientific investigations. Based on the extensive available scientific evidence we conclude that glyphosate-based herbicides, as typically employed in planted forest management, do not pose a significant risk to humans and the terrestrial and aquatic environments.

Young Norway spruce stands (Picea abies[L.] Karst) are typically cleaned of non-crop species on one or several occasions during young stand stage. In order to objectively evaluate the perceived benefits of early cleaning (EC), we studied the effects of EC on three study sites 2–2.5 years after receiving the treatment. Experiments were established as a randomised complete block design with a total of 40 blocks. Although height growth and mortality were not significantly affected, we found that EC substantially reduced canopy competition and, consequently, the mean diameter of released spruce grew 21–32% faster depending on the site. Furthermore, non-crop trees that were cleared during EC had fewer sprouts in two of the three sites and the sprouts were substantially smaller than the corresponding non-crop trees on control in all sites. EC can reduce the cost of pre-commercial thinning because EC reduced the estimated time needed for subsequent management by 18–49%. Thus, EC offers forest owners and managers an economically viable young stand management option. [ABSTRACT FROM AUTHOR]

There is increasing pressure to manage forests for multiple objectives, including ecosystem services and biodiversity, alongside timber production. However, few forests are currently co-managed for timber and wildlife, despite potential economic and conservation benefits. We present empirical data from a commercial Norway spruce ( Picea abies) and Scots pine ( Pinus sylvestris) production system in southern Norway in which moose ( Alces alces) are an important secondary product. Combining long-term hunting and forestry records, we identified temporal variation in clear-felling over the past five decades, peaking in the 1970s. Herbicide treatment of regenerating stands and a fivefold increase in moose harvest has lead to a reduction in availability of successional forest per moose of >90 % since the 1960s. Field estimates showed that spraying with the herbicide glyphosate reduced forage availability by 60 and 96 % in summer and winter, respectively, 4 years after treatment. It also reduced moose use and habitat selection of young spruce stands compared with unsprayed stands. Together these lines of evidence suggest that forest management led to an increase in moose carrying capacity during the 1970s and a subsequent decline thereafter. This is likely to have contributed to observed reductions in moose population productivity in southern Norway and is counter to sustainable resource management. We therefore call for better integration and long-term planning between forestry and wildlife management to minimise forest damage and the development of large fluctuations in ungulate populations. [ABSTRACT FROM AUTHOR]

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

By increasing resource availability, canopy opening enhances tree recruitment as well as the development of neighbouring vegetation. The proliferation of early successional and highly competitive vegetation may have dramatic consequences on seedling establishment. However, differences in competitive abilities have been shown among the plant growth forms commonly encountered in forests. We may thus expect that vegetation management leading to control of different plant growth forms would have different consequences on tree seedling growth and development. To test this hypothesis, we analysed the effects of an intensity gradient of four vegetation control treatments (untreated, coppice control, coppice and non-tree plant control, and coppice, non-tree and pioneer (tree) plant control) on plant species richness and natural tree regeneration in three post-storm sites. Higher plant species richness and a better natural tree regeneration were observed in the more intensive treatments that significantly improved the balance of the relative abundance of tree species. Suppressing the more competitive vegetation, mainly Rubus fruticosus and graminoids, led to the recruitment and growth of tree species sensitive to competition and good tree species diversity. Practical recommendations in terms of vegetation control relative to tree regeneration and plant species richness are given. [ABSTRACT FROM AUTHOR]

Abstract: On some landscapes periodic fire may be necessary to develop and maintain oak-dominated savannas. We studied the effects of two annual prescribed burns to determine their effect on microbial activity and soil and litter nutrients 1 year after the last burn. Surface litter and soil from the upper 0–5cm soil layer in three developing savannas (oak-hickory, Quercus-Carya), oak-hickory-pine (Quercus-Carya-Pinus), and pine (Pinus) were collected one year after the second of two annual prescribed burns. Surface litter was analyzed for nutrients and soil was analyzed for phospholipid fatty acids (PLFAs) and nutrients. Surface litter chemistry differed across the three savannas for potassium (K) and boron (B), being significantly (P <0.05) higher for unburned forest than for burned forest. Among savannas, only sulfur (S) was higher for the pine savanna and B for the oak-hickory savanna, both were higher for unburned forest than for burned forest. For soil, calcium (Ca) and B differed across savannas, being higher for burned forest than for unburned forest. Among savannas, soil pH, Ca, and B concentrations were higher in soil from burned forest than from unburned forest. Total PLFA differed among savannas, but was not affected by burning treatments. However, the amounts of biomarkers for Gram-positive and Gram-negative bacteria were higher while the amount of biomarker for fungal PLFA was lower for burned forest than for unburned forest. Our results indicate that the two annual prescribed burns moderately affected PLFA microbial community structure and litter and soil nutrient concentrations. However, the long-term effects of fire on these study sites are not known and merit further study. [Copyright &y& Elsevier]

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of VertigO is the property of La Revue Electronique en Sciences de l'Environnement VertigO and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Herbicide technology has evolved with forest management in North America over the past 60 years and has become an integral part of modern forestry practice. Forest managers have prescribed herbicides to increase reforestation success and long-term timber yields. Wildlife managers and others interested in conserving biodiversity, however, have often viewed herbicide use as conflicting with their objectives. Do herbicides increase forest productivity, and are they compatible with the objectives of wildlife management and biodiversity conservation? Results from the longest-term studies (10-30 years) in North America suggest that the range of wood volume yield gains from effectively managing forest vegetation (primarily using herbicides) is 30-450% in Pacific Northwest forests, 10-150% in the southeastern forests, and 50-450% in northern forests. Most of the 23 studies examined indicated 30-300% increases in wood volume yield for major commercial tree species and that gains were relatively consistent for a wide range of site conditions. Meeting future demands for wildlife habitat and biodiversity conservation will require that society's growing demand for wood be satisfied on a shrinking forestland base. Increased fiber yields from intensively managed plantations, which include the use of herbicides, will be a crucial part of the solution. If herbicides are properly used, current research indicates that the negative effects on wildlife usually are short-term and that herbicides can be used to meet wildlife habitat objectives. [ABSTRACT FROM AUTHOR]

A system for examining the effects of hardwood density and cover of herbaceous components on mean size in newly established loblolly pine plantations was developed using a site preparation study located in the piedmont province of Georgia (USA). Multispecies density models were derived to predict the sum of crown heights for eight important hardwood species using both the current or age 1 number of rootstocks and herbaceous vegetation to account for intra- and interspecific effects. The predicted sums of crown heights for the woody species were then used as predictors of mean height, diameter, and volume for loblolly pine. A seemingly unrelated regression procedure was used to compensate for correlations in error components within each system of equations that result from using predicted crown heights as regressor variables. The effects of varying sweetgum density and andropogon cover on the inter-related components of the systems based on current and age 1 competition were examined for mean height and mean diameter of the planted loblolly pines. The cumulative impacts of associated vegetation on loblolly pine growth and the relative sensitivity of height and diameter to competing vegetation were demonstrated. [ABSTRACT FROM AUTHOR]

Site preparation is used to favor seedling regeneration and establishment by enhancing growing conditions and increasing resource availability, yet few studies have compared different site preparation techniques on growth and yield of trees over multiple decades. We destructively sampled 34-year old trees of western white pine (Pinus monticola Douglas ex D. Don) and Interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco planted at two sites using a replicated experiment to test the effectiveness of different site preparation treatments: (1) no site preparation, (2) scalping, (3) bedding, and (4) bedding plus three years of competition control with herbicide. Growth and yield were compared among the treatments, and models of growth were developed for each species and treatment combination. The herbicide treatment was the only treatment that consistently improved growth and yield of both species resulting in 19%–30% gains in height, 43%–63% gains in diameter, and 31%–109% gains in stem volume by age 34. Height growth response to herbicide was sustained until age 14 for white pine and age 12 for Douglas-fir, while the diameter response was sustained until age 23 for white pine and 20 for Douglas-fir. The later peak in growth for white pine suggests a better response to treatment and that the species was able to maintain higher growth following crown closure. Both species exhibited a Type 2 growth response to herbicide, suggesting competition control resulted in sustained gains over time with associated age shifts of 8.5 and 9.7 years for white pine and 7.1 and 10.2 years for Douglas-fir, height and diameter, respectively. This compares to scalping and bedding which produced no detectable difference in growth compared to the control, and in some instances, reduced growth. In the Northern Rocky Mountains, moisture is most limiting. This is likely why trees showed the greatest response to competition control. Interestingly, this growth was sustained well beyond seedling establishment. [ABSTRACT FROM AUTHOR]

Herbicide use in forestry is analysed from an historical and environmental perspective. First chemical herbicides were developed during the Second World War. Organochloride herbicides were widely used in the past but they are now classified as very harmful for human and the environment. However, recently developed herbicides like glyphosate present the same efficiency and a much lower toxicity. In general, the public opinion about herbicides is strongly negative. In Québec, all herbicides were banned from use in public forest after some environmental assessments. This decision seems to be more politically than scientifically based. In the case of intensive managed forest, mechanical treatments with forest tractors can present similar or even lower environmental impacts than glyphosate, but few studies exist to make an objective comparison. Furthermore, in terms of tree growth, low toxicity herbicides seem to present higher effectiveness than mechanical treatments. This possible growth gain can then be used to reduce pressure on natural forest by increasing protected areas and the use of ecosystem forest management. Nevertheless, the use of herbicides must be strictly monitored to reduce environmental risks.